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<div class="moz-cite-prefix">Hello,<br>
<br>
As promised I'm sharing results for PostgreSQL and MongoDB
(attached). <br>
Please note that numbers are a bit different since MongoDB
contains results collected during 4,5 hours and PostgreSQL only
for 1 hour.<br>
<br>
As expected PostgreSQL shows results similar with MySQL (since
amount of rollbacks is the same). It created a high cpu load on
ceilometer-collector (~85%) and psql (~100%) processes.<br>
<br>
results with MongoDB are much better: collector consumes 5-30% cpu
and prof shows that profiling overhead becomes visible and cpu
spends a lot of time in _lsprof.so.<br>
<br>
Cause of this results I wonder what licensing problems we have in
promoting MongoDB as prefered/default storage?<br>
I've read AGPL license trying to understand your reasoning against
it but I cannot find anything that can be potentially dangerous
(since we are not modifying MongoDB itself).<br>
Could you please tell me if I'm wrong and point me to the right
place?<br>
<br>
Regards.<br>
<br>
On 03/21/2014 05:58 PM, Doug Hellmann wrote:<br>
</div>
<blockquote
cite="mid:CADb+p3QP7z2eGCvizoiG1hgq_Ttj-HmYC_PPQbe4b2jk=ABrRQ@mail.gmail.com"
type="cite">
<div dir="ltr">
<div class="gmail_default" style="font-size:small"><br>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Fri, Mar 21, 2014 at 7:04 AM, Sean
Dague <span dir="ltr"><<a moz-do-not-send="true"
href="mailto:sean@dague.net" target="_blank">sean@dague.net</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="">On 03/20/2014 06:18 PM, Joe Gordon wrote:<br>
><br>
><br>
><br>
> On Thu, Mar 20, 2014 at 3:03 PM, Alexei Kornienko<br>
</div>
<div class="">> <<a moz-do-not-send="true"
href="mailto:alexei.kornienko@gmail.com">alexei.kornienko@gmail.com</a>
<mailto:<a moz-do-not-send="true"
href="mailto:alexei.kornienko@gmail.com">alexei.kornienko@gmail.com</a>>>
wrote:<br>
><br>
> Hello,<br>
><br>
> We've done some profiling and results are quite
interesting:<br>
> during 1,5 hour ceilometer inserted 59755
events (59755 calls to<br>
> record_metering_data)<br>
> this calls resulted in total 2591573 SQL
queries.<br>
><br>
> And the most interesting part is that 291569
queries were ROLLBACK<br>
> queries.<br>
> We do around 5 rollbacks to record a single
event!<br>
><br>
> I guess it means that MySQL backend is
currently totally unusable in<br>
> production environment.<br>
><br>
><br>
> It should be noticed that SQLAlchemy is horrible
for performance, in<br>
> nova we usually see sqlalchemy overheads of well
over 10x (time<br>
> nova.db.api call vs the time MySQL measures when
slow log is recording<br>
> everything).<br>
<br>
</div>
That's not really a fair assessment. Python object
inflation takes time.<br>
I do get that there is SQLA overhead here, but even if you
trimmed it<br>
out you would not get the the mysql query time.<br>
<br>
That being said, having Ceilometer's write path be highly
tuned and not<br>
use SQLA (and written for every back end natively) is
probably appropriate.<br>
</blockquote>
<div><br>
</div>
<div>
<div class="gmail_default" style="font-size:small">I have
been working to get Mike Bayer (author of SQLAlchemy) to
the summit in Atlanta. He is interested in working with
us to improve SQLAlchemy, so if we have specific
performance or feature issues like this, it would be
good to make a list. If we have enough, maybe we can set
aside a session in the Oslo track, otherwise we can at
least have some hallway conversations.</div>
<div class="gmail_default" style="font-size:small"><br>
</div>
<div class="gmail_default" style="font-size:small">Doug</div>
<br>
</div>
<div> </div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div class="HOEnZb">
<div class="h5"><br>
-Sean<br>
<br>
--<br>
Sean Dague<br>
Samsung Research America<br>
<a moz-do-not-send="true" href="mailto:sean@dague.net">sean@dague.net</a>
/ <a moz-do-not-send="true"
href="mailto:sean.dague@samsung.com">sean.dague@samsung.com</a><br>
<a moz-do-not-send="true" href="http://dague.net"
target="_blank">http://dague.net</a><br>
<br>
</div>
</div>
<br>
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